Shaped laser gain medium

Abstract

The present invention provides a special-shaped laser gain medium, comprising a first gain crystal and a second gain crystal: the first gain crystal is provided with a first incident surface and a first exit surface, pump light enters the first gain crystal through the first incident surface, and the pump light is output to the second gain crystal through the first exit surface after multiple reflections in the first gain crystal; the second gain crystal is provided with a second incident surface and a second exit surface, pump light is transmitted to the second incident surface through the first exit surface, pump light enters the second gain crystal through the second incident surface, and is output through the second exit surface after multiple reflections in the second gain crystal. The present invention realizes the folded transmission of pump light in the two-dimensional direction in the gain medium, effectively increases the transmission length of pump light in the gain medium, ensures the long-distance absorption of pump light, can significantly reduce the size in the one-dimensional direction, can realize both the pump-free coupling device and the long-distance transmission of pump light in the gain medium.

Description

Technical Field

[0001] The invention relates to the technical field of solid lasers, and in particular to a special-shaped laser gain medium. Background Art

[0002] Small pulsed solid-state lasers are widely used in small laser rangefinders and small target indicators due to their compact size and high beam quality, meeting the ranging and target indication requirements of small optoelectronic systems. However, the solid-state laser gain media in commercial products and defense products on the market are mostly designed in the form of rods or slabs, combined with temperature control methods to achieve pulsed laser output. Current solid-state lasers mainly use LD side pumping solutions and end pumping technology under long pump transmission paths.

[0003] The structure of the LD side pumping scheme is as follows Figure 1 As shown, the laser gain medium used is in the shape of a rod or a slab, and is mainly composed of an LD heat sink 11, a TEC cooling sheet 12, an LD pump source 13, and a Nd:YAG slab crystal 14. Although there may be no pump coupling device, since the cross-sectional scale of Nd:YAG in a small laser is usually about 5 mm, and its absorption length for pump light is about 10 mm, the scale is relatively short. When the external ambient temperature changes, most of them can only ensure the stability of the pump wavelength through temperature control, so a higher power consumption is required to ensure the normal operation of the laser. In addition, since it is necessary to ensure sufficient gain length, the slab or rod-shaped medium needs to be tens of millimeters in the one-dimensional length direction, which is not conducive to the miniaturization of the system.

[0004] The structure of the end pump technology under long pump transmission path is as follows Figure 2 As shown, it is mainly composed of LD heat sink 11, LD pump source 13, pump coupling system 15 and Nd:YAG slab crystal 14. Since the light-emitting surface size of the LD array pump light source is usually large, it is necessary to use pump coupling to couple as much pump light as possible into the Nd:YAG crystal, and it is necessary to use a pump coupling device to compress and shape the pump light and then introduce it into the crystal. Although this ensures a long absorption length and reduces the temperature sensitivity and power consumption of the system, it is not conducive to the miniaturization design of the laser because the length of the pump coupling system and the crystal is greatly extended in one-dimensional direction. Summary of the invention

[0005] The present invention provides a special-shaped laser gain medium, which is used to solve the defects of the pump technology in the prior art, such as difficulty in taking into account the absence of a pump coupling device and long-distance pumping, and disadvantageous for the miniaturization design of a laser. The present invention realizes the folded transmission of pump light in a two-dimensional direction in a gain medium, effectively increases the transmission length of the pump light in the gain medium, ensures the long-distance absorption of the pump light, and can significantly reduce the size in one-dimensional direction compared with the traditional end-face pumping configuration, so as to realize both the absence of a pump coupling device and the long-distance transmission of the pump light in the gain medium.

[0006] The present invention provides a special-shaped laser gain medium, comprising a first gain crystal and a second gain crystal:

[0007] The first gain crystal is provided with a first incident surface and a first exit surface, the pump light enters the first gain crystal through the first incident surface, and the pump light is output to the second gain crystal through the first exit surface after multiple reflections in the first gain crystal;

[0008] The second gain crystal is provided with a second incident surface and a second exit surface. The pump light is transmitted to the second incident surface through the first exit surface. The pump light enters the second gain crystal through the second incident surface and is output through the second exit surface after multiple reflections in the second gain crystal.

[0009] According to a special-shaped laser gain medium provided by the present invention, an anti-reflection film is arranged on the first incident surface.

[0010] According to a special-shaped laser gain medium provided by the present invention, at least one first reflection surface is further provided on the first gain crystal, and the first reflection surface is used to reflect pump light.

[0011] According to a special-shaped laser gain medium provided by the present invention, a total reflection film is arranged on the first reflection surface.

[0012] According to a special-shaped laser gain medium provided by the present invention, at least one second reflection surface is further provided on the second gain crystal, and the second reflection surface is used to reflect pump light.

[0013] According to a special-shaped laser gain medium provided by the present invention, the first gain crystal and the second gain crystal are used to reflect the pump light beam multiple times and make the pump light beam undergo 180° image rotation.

[0014] According to a special-shaped laser gain medium provided by the present invention, an air gap is provided between the first gain crystal and the second gain crystal.

[0015] According to a special-shaped laser gain medium provided by the present invention, at least one metal surface is disposed on the first gain crystal and the second gain crystal.

[0016] According to a special-shaped laser gain medium provided by the present invention, the special-shaped laser gain medium includes at least two first gain crystals and / or at least two second gain crystals.

[0017] According to a special-shaped laser gain medium provided by the present invention, the special-shaped laser gain medium also includes at least one third gain crystal, the pump light is output from the second exit surface to the third gain crystal, and the third gain crystal causes the pump light to be reflected multiple times in the third gain crystal.

[0018] According to a special-shaped laser gain medium provided by the present invention, a pump light source emits a pump beam to the first incident surface of the first gain crystal, the pump beam enters the first gain crystal through the first incident surface, and then the pump beam is reflected multiple times in the first gain crystal until the pump beam is reflected on the first exit surface, and then the pump beam is output to the second incident surface of the second gain crystal through the first exit surface. The pump beam enters the second gain crystal through the second incident surface, and the pump beam is transmitted to the second exit surface after multiple reflections in the second gain crystal, and then leaves the second gain crystal through the second exit surface. In this way, the pump light is folded and transmitted in the two-dimensional direction in the gain medium, which effectively increases the transmission length of the pump light in the gain medium, ensures the long-distance absorption of the pump light, and can significantly reduce the size in the one-dimensional direction compared to the traditional end-face pumping configuration, which can realize both the pump-free coupling device and the long-distance transmission of the pump light in the gain medium. Moreover, the pump light beam realizes image transfer after multiple reflections in the first gain crystal and the second gain crystal, which compensates for the uniformity of pump light absorption to a certain extent. The uniform absorption distribution will help reduce the laser beam distortion and realize laser beam distortion compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a structural schematic diagram of the LD side pumping solution in the prior art;

[0021] Figure 2 It is a schematic diagram of the structure of an end pump under a long pump transmission path in the prior art;

[0022] Figure 3 It is a schematic diagram of the structure of the special-shaped laser gain medium provided by the present invention;

[0023] Figure 4 This is one of the structural schematic diagrams of the first gain crystal of the special-shaped laser gain medium provided by the present invention;

[0024] Figure 5 This is the second structural schematic diagram of the first gain crystal of the special-shaped laser gain medium provided by the present invention;

[0025] Figure 6 This is one of the structural schematic diagrams of the second gain crystal of the special-shaped laser gain medium provided by the present invention;

[0026] Figure 7 This is the second structural schematic diagram of the second gain crystal of the special-shaped laser gain medium provided by the present invention;

[0027] Reference numerals:

[0028] 11: LD heat sink; 12: TEC cooling sheet; 13: LD pump source;

[0029] 14: Nd:YAG slab crystal; 15: pump coupling system; 3: first gain crystal;

[0030] 4: second gain crystal; 31: first incident surface; 32: first exit surface;

[0031] 33: first reflection surface; 41: second incident surface; 42: second exit surface;

[0032] 43: second reflecting surface; 321: reflecting section; 322: emitting section. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The following is combined with Figure 3 To Attachment Figure 7 The shaped laser gain medium of the present invention is described.

[0035] As attached Figure 3 As shown, the special-shaped laser gain medium includes a first gain crystal 3 and a second gain crystal 4 .

[0036] Specifically, the first gain crystal 3 is provided with a first incident surface 31 and a first exit surface 32. The pump light enters the first gain crystal 3 through the first incident surface 31. The pump light is reflected multiple times in the first gain crystal 3 and then output to the second gain crystal 4 through the first exit surface 32.

[0037] The second gain crystal 4 is provided with a second incident surface 41 and a second exit surface 42. The pump light is transmitted to the second incident surface 41 through the first exit surface 32. The pump light enters the second gain crystal 4 through the second incident surface 41 and is output through the second exit surface 42 after multiple reflections in the second gain crystal 4.

[0038] When in use, a pump light source emits a pump beam to the first incident surface 31 of the first gain crystal 3, and the pump beam enters the first gain crystal 3 through the first incident surface 31, and then the pump beam is reflected multiple times in the first gain crystal 3 until the pump beam is reflected on the first exit surface 32, and then the pump beam is output to the second incident surface 41 of the second gain crystal 4 through the first exit surface 32. The pump beam enters the second gain crystal 4 through the second incident surface 41, and the pump beam is transmitted to the second exit surface 42 after multiple reflections in the second gain crystal 4, and then leaves the second gain crystal 4 through the second exit surface 42. In this way, the pump light is folded and transmitted in the two-dimensional direction in the gain medium, which effectively increases the transmission length of the pump light in the gain medium, ensures the long-distance absorption of the pump light, and can significantly reduce the size in the one-dimensional direction compared with the traditional end-face pumping configuration, so that both the pump-free coupling device and the long-distance transmission of the pump light in the gain medium can be realized. Moreover, the pump light beam realizes image transfer after multiple reflections in the first gain crystal 3 and the second gain crystal 4, which compensates for the uniformity of pump light absorption to a certain extent. The uniform absorption distribution will help reduce the laser beam distortion and realize laser beam distortion compensation.

[0039] In an optional embodiment of the present invention, the first gain crystal 3 and the second gain crystal 4 are, for example, Nd:YAG crystals or Nd 3+ :GdVO4 crystal or Nd 3+ :YVO4 crystal. However, it should be understood that the first gain crystal 3 and the second gain crystal 4 can also be any other suitable gain medium crystals.

[0040] Furthermore, an air gap is provided between the first gain crystal 3 and the second gain crystal 4. When in use, the total reflection and transmission of the pump light at different angles of the second incident surface 41 can be effectively ensured.

[0041] In an optional embodiment of the present invention, the width of the air gap is, for example, 200-300 μm. However, it should be understood that the width of the air gap may also be any other suitable size.

[0042] Further, as attached Figure 4 , Attachment Figure 5 , Attachment Figure 6 and attached Figure 7 As shown, at least one metal surface 5 is provided on each of the first gain crystal 3 and the second gain crystal 4. When in use, by metallizing at least one surface of the first gain crystal 3 and the second gain crystal 4, micro-connection of the two crystals on a high thermal conductivity heat sink can be achieved, which has a good heat dissipation effect.

[0043] Further, as attached Figure 3 and attached Figure 5 As shown, at least one first reflection surface 33 is also provided on the first gain crystal 3, and the first reflection surface 33 is used to reflect the pump light. When in use, the pump light enters the first gain crystal 3 through the first incident surface 31, and the pump light is reflected multiple times between the first incident surface 31, the first exit surface 32 and the plurality of first reflection surfaces 33. Finally, the first reflection surface 33 reflects the pump light to the first exit surface 32, so that the pump light is transmitted to the second gain crystal 4 through the first exit surface 32 for secondary reflection. The pump light is folded and transmitted in a two-dimensional direction in the first gain crystal 3 and the second gain crystal 4, which effectively increases the transmission length of the pump light in the first gain crystal 3 and the second gain crystal 4, ensures the long-distance absorption of the pump light, and can effectively reduce the length of the gain crystal in a one-dimensional direction, which is conducive to the miniaturization design of the laser.

[0044] In an optional embodiment of the present invention, a first reflection surface 33 is provided on the first gain crystal 3, and the pump light enters the first gain crystal 3 through the first incident surface 31 and is incident on one end of the first exit surface 32, and then the pump light is reflected on the first reflection surface 33, and the first reflection surface 33 reflects the pump light to the other end of the first exit surface 32, so that the pump light passes through the first exit surface 32 and is transmitted to the second gain crystal 4. However, it should be understood that the size of the first reflection surface 33 can be increased or decreased according to actual conditions.

[0045] Specifically, as attached Figure 5 As shown, an anti-reflection film is provided on the first incident surface 31. When in use, the anti-reflection film is plated on the outer surface of the first incident surface 31, and the pump light source emits a pump light beam to the first incident surface 31. The pump light beam passes through the anti-reflection film and enters the first gain crystal 3. The anti-reflection film is provided to ensure high-efficiency incident of the pump light.

[0046] In an optional embodiment of the present invention, the thickness of the anti-reflection film is, for example, 790 nm to 812 nm. However, it should be understood that the thickness of the anti-reflection film may also be any other suitable thickness.

[0047] Specifically, as attached Figure 5As shown, a total reflection film is disposed on the first reflection surface 33. When in use, the pump light total reflection film is plated on the first reflection surface 33, so that when the pump light is irradiated on the first reflection surface 33, the high-efficiency reflection of the pump light is effectively guaranteed.

[0048] In an optional embodiment of the present invention, the wavelength range of the total reflection film is, for example, 790 nm to 812 nm. However, it should be understood that the wavelength range of the total reflection film may also be any other suitable range.

[0049] Among them, as attached Figure 4 As shown, one end of the first exit surface 32 is a reflection section 321, and the other end of the first exit surface 32 is an exit section 322, wherein the reflection section 321 is used to reflect the pump light, and the exit section 322 is used to output the pump light transmitted to the exit section 322 to the second gain crystal 4. When in use, the pump light enters the first gain crystal 3 through the first incident surface 31, and then the pump light is transmitted to the reflection section 321, the reflection section 321 reflects the pump light to the first reflection surface 33, and the first reflection surface 33 reflects the pump light to the exit section 322, so that the pump light can be output to the second gain crystal 4 through the exit section 322.

[0050] Further, as attached Figure 3 , Attachment Figure 6 and attached Figure 7 As shown, at least one second reflection surface 43 is also provided on the second gain crystal 4, and the second reflection surface 43 is used to reflect the pump light. When in use, the pump light is transmitted to the second incident surface 41 through the first exit surface 32 after multiple reflections in the first gain crystal 3, and then the pump light enters the second gain crystal 4 through the second incident surface 41, and then the pump light is reflected multiple times between the second incident surface 41, the second exit surface 42 and the plurality of second reflection surfaces 43, until the second reflection surface 43 reflects the pump light onto the second exit surface 42 and the pump light leaves the second gain crystal 4 through the second exit surface 42. The pump light is folded and transmitted in a two-dimensional direction in the second gain crystal 4, which effectively increases the transmission length of the pump light in the second gain crystal 4, ensures the long-distance absorption of the pump light, and can effectively reduce the length of the second gain crystal 4, which is conducive to the miniaturization design of the laser.

[0051] In an optional embodiment of the present invention, a second reflection surface 43 is provided on the second gain crystal 4, the pump light enters the second gain crystal 4 through the second incident surface 41, and then the pump light is incident on the second exit surface 42, the second exit surface 42 reflects the pump light to the second reflection surface 43, the second reflection surface 43 reflects the pump light to the second incident surface 41, and then the second incident surface 41 reflects the pump light to the second exit surface 42 and leaves the second gain crystal 4 through the second exit surface 42. However, it should be understood that the number of the second reflection surfaces 43 can be increased or decreased according to actual conditions.

[0052] Further, as attached Figure 1 As shown, the first gain crystal 3 and the second gain crystal 4 are used to reflect the pump beam multiple times and make the pump beam undergo 180° image rotation. When in use, the pump beam is reflected multiple times in the first gain crystal 3 and the second gain crystal 4. When the pump beam is output from the second gain crystal 4, that is, the beam can be rotated 180° each time in the complete optical path. Combined with the resonant cavity design, the laser beam distortion caused by the pumping inhomogeneity can be compensated. In the design of the laser amplifier, when the special-shaped laser gain medium of the present invention is used as the oscillation stage and the amplification stage, there is no need to use image rotation devices such as Dove prisms between the stages, that is, 180° inversion can be achieved, and the beam distortion caused by the uneven total gain of the laser can be effectively compensated.

[0053] Furthermore, the special-shaped laser gain medium includes at least two first gain crystals 3 and / or at least two second gain crystals 4. When in use, the pump light source emits a pump light beam to the first first gain crystal 3 for multiple reflections, and then the pump light beam is reflected multiple times by multiple first gain crystals 3 and multiple second gain crystals 4 in sequence, thereby realizing long-distance transmission of the pump light beam in the gain medium.

[0054] Further, as attached Figure 1 As shown, the special-shaped laser gain medium also includes at least one third gain crystal, and the pump light is output from the second exit surface 42 to the third gain crystal, and the third gain crystal makes the pump light reflect multiple times in the third gain crystal. When in use, the pump light is reflected multiple times in the first gain crystal 3, the second gain crystal 4 and the third gain crystal in sequence, thereby realizing the folded transmission of the pump light in the two-dimensional direction in the gain medium, effectively increasing the transmission length of the pump light in the gain medium, ensuring the long-distance absorption of the pump light, and significantly reducing the size in the one-dimensional direction compared to the traditional end-face pumping configuration, which can realize both the absence of pump coupling devices and the long-distance transmission of the pump light in the gain medium.

[0055] In an optional embodiment of the present invention, the first gain crystal 3, the second gain crystal 4 and the third gain crystal are connected together, for example, by means of an air gap, bonding or adhesion. However, it should be understood that the first gain crystal 3, the second gain crystal 4 and the third gain crystal can also be connected by any other suitable means.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A special-shaped laser gain medium, characterized in that: Including the first gain crystal and the second gain crystal: The first gain crystal is provided with a first incident surface and a first exit surface, the pump light enters the first gain crystal through the first incident surface, and the pump light is output to the second gain crystal through the first exit surface after multiple reflections in the first gain crystal; The second gain crystal is provided with a second incident surface and a second exit surface, the pump light is transmitted to the second incident surface through the first exit surface, the pump light enters the second gain crystal through the second incident surface, and is output through the second exit surface after multiple reflections in the second gain crystal; An anti-reflection film is arranged on the first incident surface, at least one first reflection surface is also arranged on the first gain crystal, the first reflection surface is used to reflect pump light, a total reflection film is arranged on the first reflection surface, at least one second reflection surface is also arranged on the second gain crystal, the second reflection surface is used to reflect pump light, the first gain crystal and the second gain crystal are used to reflect the pump light beam multiple times and make the pump light beam rotate 180 degrees, an air gap is arranged between the first gain crystal and the second gain crystal, and at least one metal surface is arranged on the first gain crystal and the second gain crystal.

2. The special-shaped laser gain medium according to claim 1, characterized in that: The special-shaped laser gain medium includes at least two first gain crystals and / or at least two second gain crystals.

3. The special-shaped laser gain medium according to claim 1, characterized in that: The special-shaped laser gain medium further includes at least one third gain crystal. The pump light is output from the second exit surface into the third gain crystal. The third gain crystal causes the pump light to be reflected multiple times in the third gain crystal.

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